(In reply to Christian König from comment #9)
> Please try to investigate what MythTV is actually doing different here to
> cause the page flipping to not work correctly.

It would be interesting to know why the function can_flip() in
xf86-video-ati/src/radeon_dri2.c returns FALSE. warpme, if you're familiar with
gdb, you can attach it (from ssh) to the Xorg process while MythTV is running,
set a breakpoint at that function and trace its execution. Otherwise, we may
have to modify the function to print some debugging output.